Thin-profile or button-type batteries are small, thin energy cells that are commonly used in watches and other electronic devices requiring a thin profile. A conventional thin-profile battery includes two electrodes in the form of an anode and a cathode. The electrodes are separated by a porous separator. An electrolyte is present within pores of the separator.
The internal battery components are housed within a metal casing or housing formed by first and second battery terminal housing members. Typically the housing members comprise a can and a lid and are formed from stainless steel. The can is typically in electrical contact with the cathode to form the positive battery terminal, and the lid is in electrical contact with the anode to form the negative battery terminal. The can and lid are crimped or pressed together to form a fluid-tight seal which entirely encloses the anode, cathode, separator, and electrolyte. An electrically insulating sealing gasket is provided within the primary seal between the lid and the can to electrically isolate the two housing members.
One electrode material is elemental lithium, which is typically utilized within the lid as the anode electrode. The typical anode assembly method comprises placing a piece of lithium, already in its finished anode shape, to within the center of a pre-formed lid. The lithium adheres to the lid material and the lid/lithium composite can then be easily mounted to the cathode can without dislodging the lithium. Lithium is typically available in very thin foil sheets. The cost of these sheets is an expensive design consideration and adds significantly to the cost of an end product incorporating a lithium electrode. This is especially true as the thickness of the lithium electrode falls to 5 mils and below. Exemplary processing methods are described in U.S. Pat. No. 5,480,462 entitled "Method of Forming Button-type Battery Lithium Electrodes".
This invention grew out of concerns associated with improving the manner in which battery electrodes, and in particular thin lithium electrodes are formed. In addition, this invention grew out of concerns associated with reducing the cost associated with forming thin-profile batteries which incorporate lithium electrodes.